Wireless Mesh Networks

Wireless Mesh Networks,

Definition

"A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology. Wireless mesh networks often consist of mesh clients, mesh routers and gateways.The mesh clients are often laptops, cell phones and other wireless devices while the mesh routers forward traffic to and from the gateways which may but need not connect to the Internet. The coverage area of the radio nodes working as a single network is sometimes called a mesh cloud. Access to this mesh cloud is dependent on the radio nodes working in harmony with each other to create a radio network. A mesh network is reliable and offers redundancy. When one node can no longer operate, the rest of the nodes can still communicate with each other, directly or through one or more intermediate nodes. The animation below illustrates how wireless mesh networks can self form and self heal. Wireless mesh networks can be implemented with various wireless technology including 802.11, 802.16, cellular technologies or combinations of more than one type.

A wireless mesh network can be seen as a special type of Wireless Ad-Hoc Network. A wireless mesh network often has a more planned configuration, and may be deployed to provide dynamic and cost effective connectivity over a certain geographic area. An ad-hoc network, on the other hand, is formed ad hoc when wireless devices come within communication range of each other. The mesh routers may be mobile, and be moved according to specific demands arising in the network. Often the mesh routers are not limited in terms of resources compared to other nodes in the network and thus can be exploited to perform more resource intensive functions. In this way, the wireless mesh network differs from an ad-hoc network, since these nodes are often constrained by resources." (http://en.wikipedia.org/wiki/Wireless_mesh)

Description

Explained by the Wikipedia at http://en.wikipedia.org/wiki/Wireless_mesh_network

Wireless mesh networking is mesh networking implemented over a Wireless LAN.

"This type of Internet infrastructure is decentralized, relatively inexpensive, and very reliable and resilient, as each node need only transmit as far as the next node. Nodes act as repeaters to transmit data from nearby nodes to peers that are too far away to reach, resulting in a network that can span large distances, especially over rough or difficult terrain. Mesh networks are also extremely reliable, as each node is connected to several other nodes. If one node drops out of the network, due to hardware failure or any other reason, its neighbours simply find another route. Extra capacity can be installed by simply adding more nodes. Mesh networks may involve either fixed or mobile devices. The solutions are as diverse as communications in difficult environments such as emergency situations, tunnels and oil rigs to battlefield surveillance and high speed mobile video applications on board public transport or real time racing car telemetry. The best mobile networks are those that provide a seamless handover between the mobile device and the fixed infrastructure points." (http://en.wikipedia.org/wiki/Wireless_mesh_network)

"In basic terms, the mesh provides an alternative to established methods of linking computers together and connecting them to the internet. In practice, it can be used to build large networks far more quickly and cheaply than has previously been possible. As a result, wireless networks are viable in unexpected places. New Orleans, still without a phone service after Hurricane Katrina, recently began building a free, citywide network using mesh technology, while the whole of Macedonia is now one big wireless hotspot. Networks are also providing web connections to people in the parts of the UK untouched by phone-based broadband, as well as in developing countries that have never had effective telephone networks". (from Times Online, quoted by http://www.smartmobs.com/archive/2006/01/28/wireless_mesh_n.html)

Example

From http://www.worldchanging.com/archives/003133.html :

"CUWiN -- the Champaign-Urbana community WIreless Network -- brings together a bunch of worldchanging ideas into one useful package: Free/Open Source software to create ad-hoc municipal wireless networks using recycled old PCs. The software -- which can be downloaded from cuwireless.net -- just needs to be burned onto a CD, which can then be used to boot a PC (even something as old as a 486) with a wireless card. Once the system boots, the software configures itself, looking for other nodes to connect to; the CUWiN system uses "ad hoc networking" principles to link machines together to reach the computer that's actually connected to the Internet." (http://www.worldchanging.com/archives/003133.html)

Discussion

Why Open Mesh Networks are beneficial

Mark Cooper:

"The technologies at the heart of the digital revolution are also at the heart of the deployment of open wireless networks in the spectrum commons. The potential spectrum carrying capacity has been the direct beneficiary of the convergence of progress in digital technology and the institutional development of networks. When users add radios that help by cooperating in receiving and forwarding signals, i.e. act as repeaters, carrying capacity of the network increases. Smart nodes get their expanding brainpower from decentralized computational capacity to communicate seamlessly, utilizing embedded coordination protocols.

Smart technologies in mesh networks cooperating to deliver messages also show the beginning of anti-rivalry characteristics. The ability of each node to receive and transmit messages, even when they are neither the origin nor the destination, expands the capacity of the network. This intelligence is the key to mesh networks’ immense capacity.

The Spectrum Commons in which these networks exist exhibits the characteristic of inclusiveness, since the more nodes on the net-work, the greater the value to users. The denser the nodes in the commons, the greater is the commons’ communications capacity. The combination of digital technology and network organization has turned the old logic on its head; adding users on a mesh network improves performance. Mesh Networks allow devices to share their resources dynamically, allowing more communications to take place with less power.

However, even with new technology, there is still the challenge of how to ensure cooperation among users. Since cooperation is the key to the capacity gain, if users chose not to cooperate, the mesh network will not work. Therefore, more devices are transitioning to “embed coordination” to ensure cooperation. For example, radios become smart by embedding intelligence – algorithms – that take on the functions necessary to transmit a signal after listening to the spectrum and finding available frequencies to use and determining the power necessary." (http://cyberlaw.stanford.edu/system/files/From+Wifi+to+Wikis+and+Open+Source.pdf)

More Information

Essay: Wireless Networks as Techno-social Models. By Armin Medosch.

See also the entry on Hive Networks